Select without - values from table SQL - sql

Question

I'm taking items [I1] from this SQL Server table and returning to this table as - QTY and - TOTAL ..
http://i.stack.imgur.com/bdnPF.png
After that I have another row with the same Item ID and - QTY AND -Total
http://i.stack.imgur.com/4vUNP.png
I need to filter every time without returned product,
In this case I already returned the I1, when I'm going to return sale invoice .. I need to select the none returned products,
SELECT
DEL_PurchasesLines.ItemIdentityCode,
SUM(DEL_PurchasesLines.Qty) As Qty,
SUM(DEL_PurchasesLines.Total) As Total
FROM DEL_PurchasesLines
WHERE InvoiceNo = '1' AND DealerCode = 'S0002M'
GROUP BY
DEL_PurchasesLines.ItemIdentityCode
HAVING SUM(DEL_PurchasesLines.Total) > 0 AND SUM(DEL_PurchasesLines.Qty) > 0

Answer 1

I always like to create some test data in tempdb.
--
-- Create sample data
--
use tempdb;
go
if object_id('items') > 0
drop table items
go
create table items
(
id varchar(8),
qty int,
total int
);
go
insert into items values
('I1', 2, 4),
('I2', 3, 6),
('I3', 5, 10),
('I1', -2, -4);
go
select * from items;
go
One way to solve this problem is to group by the id, summing both the qty and total columns. Display only rows that have > 0.
--
-- Show lines in which qty * total > 0
--
select id, sum(qty) as sum_qty, sum(total) as sum_total
from items
group by id
having sum(qty) > 0 and sum(total) > 0;
Another way to think of this is to show all orders that do not have returns.
--
-- Show rows that do not have any returns
--
select *
from items i left join
(
select id
from items
where qty < 0 or total < 0
) r on i.id = r.id
where r.id is null